Composition for forming a dry, homogeneous, self-adherent, lubricating film on metal stock



Patented Dec. 11, 1951 UNITED STATES t TENT QFFHCE Gilbert H. Orozco, Euclid, and Richard F. Roy, Cleveland, Ohio, assignors to Gilron Products Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application August 11, 1949, Serial No. 109,824

18 Claims. 1

This invention relates to dry lubricants for lubricating metal bars, rods, sheets, and the like, during the pressure forming thereof.

The present invention relates particularly to a composition of which an aqueous solution thereof is applied'to the metal stock and caused, or permitted, to dry thereon, thereby forming on the stock a dry homogeneous self-adherent lubricating and protecting film which, during the formation of the metal stock to the desired shape, supplies the necessary lubrication to the stock and die surfaces.

For the purposes of illustration, the present invention is described as applied in the deep drawingof sheet steel and steel alloys in pressure dies for which it is particularlyadapted, its application to drawing, stamping and shaping of other kinds of metal sheet and rod stock, to cold heading, and to wire drawing, being apparent from .the illustrative example.

The present invention in general is used for the same purposes and in the same manner as the compositions disclosed in the Whitbeck Patent No. 2,470,062, issued on May 10, 1949, and the application of Gilbert l-I. Orozco, Serial No. 53,376, filed October 7, 1948, and constitutes an improvement over such metal lubricating compositions.

In the above identified patent there is disclosed a-dry composition which comprises essentially water soluble high titre soap, having a titre or melting point of from about 36 to 42 centigrade, and borax, the soap being within the range of 10% to 33% of the composition and the borax being from about 90% to 67%. This composition is applied to the stock by dissolving it in water in an amount of about one to thirty ounces of the dry mix per gallon and then-dipping the stock therein or flowing the solution thereon and then drying the stock so as to deposit thereon a dry, homogeneous, adherent lubricating and protecting film. The lower concentrationin the aqueous solution is used for relatively bright smooth surfaces, the concentration being increased as the roughness of the surface and theporosity of the metal increases.

While the patented composition above discussed functions in the desired manner in most instances, there are certain disadvantages attendant to its under certain circumstances. ample, the patented composition is oftentimes undesirable when used in hard water since the soap present in the patented composition will oftentimes react with the metals in the hard water to form insoluble soap. The formation of I For exthese metal soaps breaks down, reduces, or destroys the adhesion of the resulting lubricating film to the metal stock and consequently the film scuffs off during initial contact with the forming die and is not carried with the metal stock into the die.

Moreover, even in soft water, the new composition of the present invention constitutes a distinct improvement over the patented composition. For example, the new compositions have been found to adhere to the surface of the metal stock regardless of the water used far better than the patented composition thus lessening any possibility of the lubricant being scuffed off during initial and subsequent contact of the metal with the die. Furthermore, the lubricating composition of the present invention provides faster initial lubrication, gives better plasticity and results in a thinner film being present on the metal stock.

It has been found that these objectionable characteristics can be eliminated and a thin film which, particularly whe hard water is used in the solution, provides the necessary lubricity and adherence at the lower die temperatures prevailing during the initial forming of the stock as well as the subsequent higher die temperatures may be had, said film being a completely water-soluble composition consisting essentially of the following ingredients and proportions by dry weight:

The high titre soaps to be employed in the present composition may be the water-soluble high titre soaps disclosed in Whitbeck Patent No. 2,470,062 and which possess a melting point of at least about 36 C., for example, from about 36 C. to 42 C. Such soaps may be palm oil soap, tallow soap, etc., or mixtures thereof and for a complete list of such materials reference is to be had to the aforesaid patent.

Also, high titre soaps possessing a melting point in excess of 42 may likewise be employed in the present composition. The melting point of the 3 higher titre soaps may be artificially raised by decreasing the fatty acid content to produce the desired material or a soap possessing a normally high melting point may be used with equal satisfactory results.

To obtain a satisfactory high titre soap by artificial means, one method by which they may be secured is the triple press process. In this process the low grade inedible tallow or other material is split by any means such as the Twitchell process (see U. S. Patent No. 601,603) to secure the desired fatty acids. The fatty acids are then charged into small shallow pans and permitted to solidify at a temperature of about 40 F. lhe resulting solid cakes are then individually wrapped in press cloths and subjected to moderate pressure in a cold hydraulic plate press to express some of the fatty acid. The residual solid is called single press soap. The single pressed cake are recast into cakes and subjected to a hot pressing in a steam or waterheated press to yield double-pressed soap. This soap is then recast and repressed at a slightly higher temperature to produce the triplepressed soap having an artificially raised melting point due to the expressing of a portion of the fatty acid from the crude tallow.

An additional artificial method is the one in which the fatty acid content has been altered chemically. For example, the fatty acid may be hydrogenated as by the process set forth in U. S. Patent No. 826,089 to alter the fatty acid content and raise the melting point of the soap.

Illustrative examples of specific high titre soaps which have high melting points naturally occurring or which have been induced by artificial means are as follows, the melting point given also: stearic acid soap (58); cocoa butter soaps (48-50); borneo tallow soap (50-52) hydrogenated tallow soap (52); coaceric (92 93); Japanic (117); palmetic acid soap (62.6); stearin flux soap obtained from refining of garbage fats (50) Any one or more of the foregoing soaps may be used separately or together in any proportions with one or more of the other soap so long as the total amount of soap employed in the composition is within the stated range and possesses the stated high melting temperature. For example, tallow soap may be admixed with palm oil soapin any desired ratio and used as a single compound in the stated amounts. Likewise, relatively low titre soaps as disclosed in the Whitbeck Patent No. 2,470,068, may be mixed with the relatively higher titre soaps and used in the same manner.

In the foregoing discussion of the high titre soaps to be employed in the composition of the present invention it is believed necessary to provide a more detailed definition as What is meant by the melting point of the soap. These melting points of the soaps as employed herein and in the appended claims do not identify the melting point of the entire soap mass. Rather, the melting point referred to means the temperature at which the fatty acid content of the soap mass melts. This melting point of the fatty acid content is normally referred to as the titre of the soap. In other words, the melting point or titre of the soap is the point at which the fatty acid content melts.

In the aforesaid composition, the polyhydric alcohol and esters thereof have been identified by a generic terminology. However, all such compounds falling within the definition of the generic class will not be found to be of utility in conjunction with the remaining ingredients to form the desired composition due to certain additional properties the alcohols or esters must possess in order to perform their intended function. These additional properties are (1) that the compounds must be water-soluble, (2) they must be inert with respect to additional ingredients present in the composition as well as the ingredients in the water, (3) they must be solid and, as hereinbefore indicated, possess a melting point of at least 40 C., (4) they must be substantially non-hygroscopic, and (5) they must possess a flash point sufficiently high that it Will not ignite from the heat of friction during the forming operation. In other words, the generic terminology employed herein and in the appended claims is intended to include only those compounds coming within the generic terminology and which in addition possesses the additional properties above enumerated. Illustrative and non-limiting examples of compounds satisfying each of the above requirements are polyethylene glycol, polyethylene glycol oleate, diglyceral stearate, propylene glycol stearate, diglycol stearate, etc.

A particularly preferred material is polyethylene glycol and may be any one of the different water-soluble compounds having a melting point of at least about 40 C. up to about C. A preferred fatty acid ester and one particularly. adapted to combine with the polyethylene glycol as a mixture is polyethylene glycol oleate. The oleic content of this material aids in providing particularly strong adhesion with a somewhat lower melting point and in addition acts, to some extent, as a plasticizer and coupler.- The following example illustrates such a composition:

It has been hereinbefore indicated that the polyhydric alcohols or esters thereof may be employed as mixtures. In the following discussion relative to such mixtures, polyethylene glycol and polyethylene glycol oleates will be employed as illustrative materials. The combined use of polyethylene glycol and the oleate is based ordinarily on the finish of the metal stock. For example, when the metal stock has a mirror finish the polyethylene glycol oleate is used alone due to the fact that it is more polar than the polyethylene glycol alone. When the metal has a smooth finish somewhat rougher than the bright mirror finish, a mixture of the oleate and the alcohol will be found necessary since a thicker film is required. However, the oleate content must not be too great since an excess in a film of the required thickness for the rougher stock would result in an excessive tackiness which is highly objectionable. This problem is not pres-- ent in the mirror finish since only a thin film is necessary and the tackiness does not become a problem. On a still rougher surface on the order of vitreous enamel stock, the polyethylene glycol must be used in an excess over that of the oleate due to the increased need for a thicker protective coating for the metal surface and the resulting likelihood of objectionable tackiness if a large amount of oleate is present. In summation therefore, the mixtures will be determined to a large extent by the surface of the metal stock with the oleates being used in excess when the surface is highly polished and requires only a thin lubricating and protecting film whereas an excess of the alcohol will be found desirable when the surface of the stock is rough. As stated above, the compounds employed in the above discussion, while preferred, are used only for illustrative purposes since other polyhydric alcohols may be used in place of the polyethylene glycol and also other fatty acid esters thereof maybe substituted for the oleate, i. e. propylene glycol stearate, glycol monostearate, diglycol stearate, etc. Moreover, there may be a mixture of the different alcohols or esters thereof in lieuof a simple mixture of an alcohol and an ester.

The following example illustrates such a mixture:

Range Preferred Parts Parts Water soluble high titre soap with a melting point of at least about 36 centigrade about 5-25.. about 10. Water soluble polyethylene glycol. about -5. Do. Water soluble polyethylene glycol oleate about 1-15.. about 5. Water soluble alkali metal borate balance. about 75.

when the lithium borate and potassium boratemay be used. Moreover, the borate to be used may consist of a mixture of the several borates with the resulting mixture being present within he tate r n e It will be observed from. the foregoing examples that slight variations in the proportions of the ingredients of the composition will occur due to the form of the alcohol or ester employed.

These variations, while slight, are of importance however, in order to insure the proper adherence of the composition film so as to provide the necessary lubrication. For example, using polyethylene glycol and an ester thereof as illustrative examples, the lowest minimum amount of polyethylene glycol that may be employed in the absence of any of the esters is 5 parts by dry weight. If an amount lower than 5 parts is employed there is insufiicient adherence of the resulting film to the surface of the metal stock and improper lubrication occurs at the low initial friction heat of the metal and the die. If the polyethylene glycol is employed in an amount in excess of more than parts dry weight the film is brittle initially but becomes thermoplastic under the heat of the die at temperatures below those commonly reached in die forming and rod and wire forming and as a result it peels off dur ing the closing of the dies or initial passage through the ring die and chills as a hard crust on the radii of the dies where the temperatures are somewhat lower.

In employing a mixture of-polyethylene glycol and polyethylene glycol oleate the proportions should be, in relation to each other, from between about five to twenty parts for the polyethylene i-glycol and from about fifteen parts to one part portant in that the lowest desirable amount of borate that is to be present is about parts by dry weight. By varying the ingredients in the above manner, the borate will always be present in the desired amount.

Having described in detail the component compounds going to make up my new and improved all-purpose, and one particularly suitable for use in hard water, lubricating composition, it becomes convenient to give a few illustrative-examples of completed compositions in dry weight:

Example 1 Parts Tallow soap 5 Polyethylene glycol 10 Borax ---.-.r-:-r.-..--.-.r-,--...- r-', Example 2 Parts Palm oil soap l0 Polyethylene glycol l2 Borax 78 Example 3 Parts Tallow soap; palm oil soap 1o, Polyethylene glycol; polyethylene glycol oleate 10 Lithium borate 80,

Example 4 Parts Cocoa butter soap 30 Polyethylene glycol oleate 5 Lithium borate 65 Example 5 Parts Stearic acid soap 5 Polyethylene glycol 30 Potassium borate 65 Example 6 Parts Borneo tallow soap 20 Glycerol monostearate; polyethylene glycol oleate 5 Potassium borate; borax 75 Example 7 Parts Hydrogenated tallow soap 5 Propylene glycol stearate 25 Lithium borate Example 8 Parts Coaceric; Japanic 10- Diglycol stearate; propylene glycol stearate 8 Lithium borate; borax 82 Example 9 Parts Palmitic acid soap 15 Diglycol stearate 5 Borax 8i 7. Example 10 I Parts Stearine soap Polyethylene glycol stearate; propylene glycol stearate 5 Lithium borate 85 Example 11 i Parts Tallow soap m Glyceryl monostearate 5 Borax 80 Emample 12 Parts Stearine soap l0 Diglycol stearate 5 Potassium borate 85 Example 13 V Parts Palmitic acid soap; tallow soap 13 Polyethylene glycol oleate 15 Borax '72 Example 14 Parts Hydrogenated tallow soap 8 Polyethylene glycol oleate 12 Borax 80 For applying the new and improved composition of the present invention to the metal prior to its formation, an aqueous solution thereof is made using the concentration of from one ounce per gallon of water to saturation, depending on the roughness of the surface of the stock and the severity of the draw. Metal stock with smooth or mirror finish can be coated sufiiciently with the concentration of four ounces per gallon for severe draws. As the roughness and porosity of the stock surface increases the concentration is increased unless a very light draw is contemplated. For very rough and porous stock such as vitreous enamel stock, a saturated solution is deemed best. For very light draws, as low as one ounce per gallon can be used on relatively smooth surface stock.

The aqueous solution as above prepared is ordinarily applied to the metal stock by a simple dipping operation and then permitted to dry whereby there is formed on the surface of the metal stock, a dry homogeneous, self-adherent lubricating and protecting film. The metal stock containing the film is then pressure formed into the desired shape without any detriment to the dies or the surface of the metal. sired formation the formed article is then washed with water thereby removing completely any traces of the lubricating film. In other words, after the washing step, the surface is then ready to receive any subsequent operation, i. e. vitreous enameling, painting, electroplating, etc., without any additional washing, cleaningor pickling operation.

It should be particularly noted that the aqueous solution of the composition may be applied to the metal stock and the lubricating film per-- mitted to dry thereon. The coated metal stock may then be stored and not formed into the desired shape until some future date. The unique feature or characteristic of the composition is extremely advantageous since it permits the metal manufacturer or steel mill operator to provide small metal fabricators with metal already con taining a lubricating and protecting film. When such a procedure is employed it should be men- After the detioned that borax should be employed as theborate since it has been found so essential in holding the film in a dry and homogeneous state. However, in such circumstances, a mixture of alkaline earth metal borates may be employed so long as borax is present in the predominating amount. In other words, the borate may consist of a major amount of borax and minor amount of lithium or potassium borate. Such a mixture has been found advantageous for many purposes where the fabrication occurs shortly after the application of the aqueous solution.

Where the metal stock is dipped in the water solution and dried and then passed within a very short time to the forming dies, potassium or lithium borate, either alone or in admixture, will be found to be of utility. Under such circumstances certain objectionable characteristics of these borates, i. e., tendency to disperse the polyhydric compounds, are not encountered due to the prompt fabrication. Therefore, borax is the preferred borate due to its utility for all purposes although the remaining alkali metal borates possess utility when employed properly.

In employing a mixture of borax and another borate. itshould be noted that as the proportion of borax increases, the softness and tackiness oi the film decreases. In other words, the remaining borates may be admixed with the borax to control the plasticity and tackiness of the dry, homogeneous film.

Under many circumstances, additional materials will be found desirable due to the particular stock used and the state of its surface. It has been found that under many circumstances it will be advantageous to add a small amount, 1. e. about A2 to 5 parts, of a coupling agent. The coupling agent must be inert with respect to the Water employed in forming a solution of the composition and must also possess the well-known properties of surface active agents. Illustrative and specific compounds are dioctyl ester of sodium sulfosuc- ClIllC acid, sodium petroleum sulfonate, alkyl naphthalene sulfonates, dibutyl phenyl phenol sodium sulfonate, cetyl trimethyl ammonium bromide, sodium alkyl sulfates i. e. sodium lauryl sulfate, sodium octyl sulfate, etc., potassium lauryl sulfate, potassium octyl sulfate, amino fatty acid esters, polyoxyalkylene di-fatty acid esters, alkyl aryl sulfonates i. e. Nacconol NR, etc.

The term consisting of as employed herein and in the appended claims to define the coating composition or film formed thereby is intended to define a composition or film containing the claimed ingredients, in the relative ranges stated, as the active constituents of such composition or film but is not meant to exclude the presence of minor amounts of conventional compounds or ingredients, whether lubricating or not, the use of which is common in the lubrication of metals during the forming operations, nor it is meant to exclude small amounts of coupling and surface active agents such, for example, as pointed out above.

Having thus described our invention, we claim:

1. A coating material for admixture with Water for coating a piece of unformed metal stock and the like and forming thereon a self-adherent, homogeneous lubricating and protecting film consisting essentially of the following ingredients by weight:

Water-soluble high titre soap having a melting point of at least about 36 0., 5-30 parts; watersoluble material having a melting point of at least about 40 C. and selected from the group consistmg of polyethylene glycol, fatty acid esters of aliphatic polyhydric alcohols having less than four hydroxy groups, and any mixtures of any two or more of the recited ingredients, 30-5 parts; water-soluble alkali metal borate, balance (65 parts minimum).

2. A coating composition in accordance with claim 1 wherein the water-soluble high titre soap possesses a melting point of at least about 36 C.

3. A coating composition in accordance with claim 1 wherein the water-soluble high titre soap possesses a melting point about 42 C.

4. A coating composition in accordance with claim 1 wherein the water-soluble high titre soap consists of a mixture of soaps which possesses a melting point of at least about 36 C.

5. A coating composition in accordance with claim 1 wherein the soap is tallow soap having a melting point of at least about 36 C.

6. A coating composition in accordance with claim 1 wherein the soap is palm oil soap having a melting point of at least about 36 C.

7. A coating composition in accordance with claim 1 wherein the soap is stearin flux soap.

8. A coating composition in accordance with claim 1 wherein the polyhydric material is a water-soluble fatty acid ester of an aliphatic polyhydric alcohol having less than four hydroxy groups.

9. A coating composition in accordance with claim 1 wherein the polyhydric material is polyethylene glycol oleate.

10. A coating material in accordance with claim 1 wherein the borate is borax.

11. A coating material in accordance with claim 1 wherein the borate is lithium borate.

12. A coating material in accordance with claim 1 wherein the borate is a mixture of borates.

13. A coating material in accordance with claim 1 wherein the borate is potassium borate.

14. A coated metal article comprising an unformed metal stock and a thin film covering said stock, the film comprising the composition set forth in claim 1.

15. A coating material for admixture with water for coating a piece of unformed metal stock and the like and forming thereon a self-adherent, homogeneous lubricating and protecting film consisting essentially of the following ingredients by weight:

Water-soluble high titre soap having a melting point of at least about 36 C., 10-15 parts; water-soluble material having a melting point of at least about 40 C. and selected from the group consisting of polyethylene glycol, fatty acid esters of aliphatic polyhydric alcohols having less than four hydroxy groups, and any mixtures of any two or more of the recited ingredients, 5-15 parts; water-soluble alkali metal borate, 80-70 parts.

A coating material for admixture with water for coating a piece of unformed metal stock and the like and forming thereon a self-adherent, homogeneous lubricating and protecting film consisting essentially of the following ingredients by weight:

Water-soluble high titre soap having a melting point of from between 36-42 0., 5-30 parts; polyethylene glycol having a melting point of at least about 40 C., 30-5 parts; borax, balance (65 parts minimum) 17. A coating material for admixture with water for coating a piece of unformed metal stock and the like and forming thereon a self-adherent, homogeneous lubricating and protecting film consisting essentially of the following ingredients by weight:

Water-soluble high titre soap having a melting point of at least about 42 0., 5-30 parts; polyethylene glycol having a melting point of at least about 40 0., 30-5 parts; borax, balance (65 parts minimum).

18. A coating material for admixture with water for coating a piece of unformed metal stock and the like and forming thereon a self-adherent, homogeneous lubricating and protecting film consisting essentiall of the following ingredients by weight:

GILBERT H. OROZCO. RICHARD F. ROY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Whitbeck Dec. 20, 1949 OTHER REFERENCES Synthetic Organic Chemicals, Carbide & Carbon Chem. Corp., 12th ed., July 1, 1945.

Number Re. 23,184 

1. A COATING MATERIAL FOR ADMIXTURE WITH WATER FOR COATING A PIECE OF UNFORMED METAL STOCK AND THE LIKE AND FORMING THEREON A SELF-ADHERENT, HOMOGENEOUS LUBRICATING AND PROTECTING FILM CONSISTING ESSENTIALLY OF THE FOLLOWING INGREDIENTS BY WEIGHT: 